In recent years, along with development of medical technology, microsurgery using a surgical microscope has been widely performed. In microsurgery, there may be a case where an assistant operator who assists the principal operator is needed in addition to the principal operator (surgeon), particularly for a complex surgery. In this case, not only the principal operator but also the assistant operator may need to observe the operation site in a magnified manner, for which a surgical microscope has been developed as disclosed in Japanese Unexamined Patent No. 2005-137932 wherein a microscope is also disposed for use by the assistant operator in addition to the microscope for use by the principal operator.
As such a microscope for use by the assistant operator, a side-view microscope is disposed at the side of the microscope (main microscope) for use by the principal operator. When the main microscope is moved by the principal operator in order to shift the observation position during the surgery, the side-view microscope is also moved because the side-view microscope is disposed to the main microscope itself. There has been an inconvenience that the assistant operator must also move accordingly.
Additionally, in order to solve the above problem, as disclosed in Japanese patent No. 2607828, a surgical microscope has been developed, comprising a video microscope which captures images of the operation site using a camera instead of the side-view microscope and displays its stereoscopic images on a small size liquid crystal display (LCD). With the surgical microscope, the above-mentioned inconvenience is solved because the video microscope can be provided independently from the main microscope. In addition, the assistant operator can observe the operation site not only from a side position of the principal operator but also from an opposite position, when the small-size LCD is moved.
However, with the main microscope disclosed in Japanese patent No. 2607828, the image observed by the assistant operator through the small-size LCD is a visual field image observed by the principal operator at his/her view point. Accordingly, there is an inconvenience that the assistant operator may be confused in grasping the sense of right-and-left or up-and-down relative to his/her standpoint. For example, if the assistant operator reaches out to the operation site when observing the operation site from a position opposite to the principal operator, the assistant operator sees his/her hand coming out from left upper side of his/her visual field. Or, if the assistant operator reaches out to the operation site when observing from a side position, he/she sees his/her hand coming out from the right side. In other words, since the assistant operator sees, through the small-size LCD, his/her hand moving in a direction different from the direction to which it is actually moving, there has been a problem that the assistant operator could not properly grasp the sense of distance, thereby preventing the assistant operator from properly assisting the principal operator.